The present invention relates to an electrode for human heart pacemaker, and to an electrode employed in the field of medical equipment, more in detail to an implantable mesh electrode, especially an electrode for reanimation (defibrillator).
A human heart pacemaker comprises a main element, an electric wire and an electrode. The performance required for an electrode especially for an implantable electrode for human heart pacemaker includes that polarizability of pulses generated from the pacemaker is low, impedance (input impedance) of signals is low when the signals from a human heart are detected, and impedance (output impedance) is high when the signals are supplied to the human heart, in addition to that the electrode can be easily adhered to the human heart. Although, accordingly, the improvements of the polarizability and the input impedance of the electrode which is formed by Pt or a Pt alloy having high electric conductivity and being harmless to a living body have been implemented by decreasing the dimension of the electrode and the polarizability for increasing the output impedance and by mechanically roughening the surface, the sufficient effects have not yet been obtained especially in connection with the polarizability and the input impedance.
Although, the further improvements have been implemented which comprises coating a mixture of Pt and a platinum metal oxide on an electrode formed by Pt or a Pt alloy, or Ti or a Ti alloy to prepare the electrode for a human heart pacemaker, much further improvements are being requested.
Further, heretofore, a mesh electrode has been employed which is formed by wire rods of Pt-Ir(10%) or Ti in the viewpoint of its electric characteristics and its suitability to human organs in the field of medical equipment or the like. However, the electrode possesses the below drawbacks.
Although the Pt-Ir(10%) possesses better electric conductivity and excellent electrode characteristics, it is inferior to the mesh electrode made of Ti in fatigue characteristics against repeated stress of heart pulsations.
Although, on the other hand, Ti is superior in such mechanical characteristics as fatigue strength and tensile strength, the Ti is made brittle by absorbing a hydrogen gas generated in humors acting as an electrolyte by means of a current during the working of the electrode.